HCG slow rise?

Anyone have success stories with a slow rising HCG? 🥺

My HCG was 4,800 and just barely under 48 hours later it was 6,900. (5-6weeks)

I had an US at 5w5d and only saw a yolk sack which didn’t concern me since the same thing happened with my now 2yr old son when I was pregnant with him as well. But my midwife seems concerned my numbers didn’t double 😞

I go back in 10 days for an US to see if there’s a fetal pole/baby with the yolk sack.